Private networks can allow companies and other organizations to provide a shared space (e.g., an intranet) for employees or organization members. A private network may be limited geographically and/or can be a virtual private network (VPN) with secure communication over an external/untrusted IP network such as the Internet.
One increasingly important aspect of private networks is the ability for network users to have access to the private network using access points outside the private network. In particular, mobile users will often access the private network using such access points and may even wish to change access points as the mobile user roams. The mobile user may even enter a geographical region served by the private network and can then change from an access point outside the private network to an access point within the private network.